Printing presses

ABSTRACT

A laboratory printing press uses an endless loop web passing around an idling impression roller and air-cushion bearings. A lever assembly acts between one of the bearings and a weight selected according to the required tension in the web. To print, the impression roller is brought by a pneumatic piston and cylinder assembly, against the driven printing cylinder with a portion of the web nipped therebetween, the roller having a low inertia. A photoelectric resolver senses the revolutions of the cylinder and is used to control the operation of the pneumatic assembly. Access to the printing cylinder and the impression roller is improved by having their shaft bearings arranged one one side only so that they are both cantilevered.

United States Patent 1191 Marshall et al.

1451 Sept. 25, 1973 PRINTING PRESSES [75] Inventors: Richard Carlile Marshall,

Harpenden; William Stuart Steer, Croxley Green, both of England [73] Assignee: Odhams (Watford) Limited,

Watford, England 221 Filed: Apr. 26, 1971 211 Appl.No.: 137,531

[30] Foreign Application Priority Data Apr. 27, 1970 Great Britain 20,193/70 52 u.s.c| ..101/151,101/219,101/247, 308/9, 15/256.3, 226/154, 226/189, 226/194 511 lnt.Cl. ..B4lp9/10 58 Field ofSearch 101/247,219, 155, 1o1/157,91,92, 167, 153, 169, 350; 226/152,

[56] References Cited UNlTED STATES PATENTS 3,288,060 ll/1966 Miller 101/219 X 3,545,373 12/1970 Spaulding 197/1 R 2,996,001 8/1961 Schlegel et a1 101/128 X 3,196,786 7/1965 Homberger et a1... 101/247 X 2,671,711 3/1954 Masson et a1 346/21 X 3,254,626 6/ 1966 Uemura 197/1 R 2,453,239 11/1948 Luhn 346/21 X 3,195,139 7/1965 Hood, Jr. 346/136 X 3,261,523 7/1966 Roecus et a1. 226/194 X 2,644,395 7/1953 Peyrebrune et a1 101/157 FOREIGN PATENTS OR APPLICATIONS 741,896 12/1955 Great Britain 101/219 741,896 12/1955 Great Britain 101/219 Primary ExaminerRobert E. Pulfrey Assistant Examiner-Eugene H. Eickholt Att0rneyWaters, Roditi, Schwartz & Nissen [5 7] ABSTRACT A laboratory printing press uses an endless loop web passing around an idling impression roller and aircushion bearings. A lever assembly acts between one of the bearings and a weight selected according to the required tension in the web. To print, the impression roller is brought by a pneumatic piston and cylinder assembly, against the driven printing cylinder with a portion of the web nipped therebetween, the roller having a low inertia. A photoelectric resolver senses the revolutions of the cylinder and is used to control the operation of the pneumatic assembly. Access to the printing cylinder and the impression roller is improved by having their shaft bearings arranged on one side only so 1 .9121392351 911199119191195991 a ,3

2 Claims, 5 Drawing Figures PATENTED SEP25I973 SHEEI 1 UF 4 TUE PATENTEUSEPZSISH 3,760,720

sum 2 OF 4 PATENTED SEP25 I975 SHEET 0F 4 1 1 PRINTING PRESSES BACKGROUND OFTHE INVENTION FIELD OFTHE'INVENTION This invention relates to printing presses. It is particularly concerned with presses for testing purposes, such as studies of paper and ink and for electrostatic assist experiments".

SUMMARY OF THE INVENTION Accordingto the present invention there is provided a printing press'including a rotary printing cylinder,

drive meanscoupled to said cylinder for driving said cylinder, guide means'positioned near said'cylinder and constructed for guiding an endless loop web so that it BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention and to show how the same may be carried into effect reference will now by made, by way of example, to the accompanying drawings, in which:

FIG. I is a side elevation of a gravure printing press for testing purposes,

FIG. 2 is a plan view of the press of FIG. 1,

FIG. 3 is an end elevation of the press of FIG. 1, FIG. 4 is a side elevation of a' doctor blade assembly used in the press of FIGS. 1, 2 and 3, and

FIG. 5 is a plan view of the doctor blade assembly of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The press shown in the drawings has a main frame 1 which is mounted on a table 2. A variable speed drive motor 3 is also mounted on the table 2 andhas a belt drive transmission 4 which will drive, in a manner described below, a paper web used in the press at any speed within a given range, for example, from 120 ft. per minute to 1,100 ft. per minute.

A gravure cylinder 4 5 mounted on a horizontal shaft 6 supported in the frame 1 and is rotated by the belt transmission 4. The shaft 6 has bearings all on the same side of the cylinder 5 so that the latter is cantilevered. The cylinder 5 is free to rotate in a partially closed chamber to which ink is supplied in the usual manner, the side of the chamber remote from the shaft 6 being defined by a door 7 having quick release catches 7a to give easy access to the cylinder, which is easily removable without the interference of bearings. A doctor blade assembly 8 is also provided in the usual manner to co-operate with the gravure cylinder. The doctor blade is reciprocated by a reciprocatory drive including a worm reduction gear indicated at 9.

Referring to FIGS. 4 and 5, the doctor blade assembly 8 comprises a body 30 to which is imparted the reciprocating drive. An end of the body 30 bears a doctor blade frame 29 and is provided with a cheese-headed adjusting screw 28 and two threaded rods 32. The frame 29 is in two halves which clamp the blade 33 between them. The doctor blade frame 29 ispivotally supported by a lower edge of the body 30 and is clamped between the head of the adjusting screw 28 and two adjusting nuts 27 which are engaged on the threaded rods32 and bear on the frame 29 at locations between the screw 28 and the lower edge of the body 30. By varying the depthto which the screw 28 projects from the body 30 and correspondingly adjusting the nuts27, the angle of contact of the doctor blade 33 with the cylinder 5 can be altered as desired. A flexible extension of the peripheral wall of the ink chamber is in contact with the underside of the doctor blade 33 to ensure that ink removed from the cylinder is returned to the'chamber.

An "angled rod 34 has one end inserted in a bore within the body 30 and is fixed there by two grub screws 36. A weight element 35 is slidably mounted on the rod 34' and, by, means of grub screws 37, may be fixed in a selected position along the rod so as to cause the doctor blade to have a desired contact pressure with the printing cylinder. The rod 34 is graduated along its length in terms of this contact pressure. The angled rod and weight member could be replaced by an adjustable spring acting on the body 30.

The frame 1 also supports a secondary, hinged frame 10, the hinge axle 11 being parallel to the shaft 6, over which'the frame 10 extends. The frame 10 carries a freely rotatable, i.e., idling, impression roller 12 of very low inertia which is cantilevered by two bearings 13 to one side of the frame 10 to overlie the cylinder 5. There are also two air bearings 14 projecting from the same side of the frame 10 for an endless loop paper web 15 indicated in chain-dotted lines in FIG. 1. These air bearings are perforated tubes which are supplied with air under pressure and through the perforations of which the air escapes to form air-cushions supporting the web 15. A pivoted pneumatic piston and cylinder assembly 16 acts between the frame 1 and the end of the frame 10 remote from the hinge axle 11 and is actuable to move the latter downwards to nip the paper web 15 between the impression roller 12 and the cylinder 5, against the action of a return spring 17 which normally maintains the impression roller 12 clear of the cylinder 5. The pneumatic assembly 16 is double acting and assists the spring 17 to return the frame 10 to its normal position.

The shaft 6 has a disc 18 fixed thereon and having, an aperture 18a near its periphery with which a photoelectric device 19 co-operates to give a signal indicative of the revolutions of the shaft 6 and hence of the cylinder 5. This electronic counting means can be used to control the duration of the impression period by governing the supply of air to the pneumatic piston and cylinder assembly 16 from its initial actuation.

A further air bearing for the web is also provided and forms part of a tensioning device 20. In the example shown in FIG. ll, this takes the form of an L-shaped lever 21 pivoted at its angle on a fixed member 22 and having the air bearing 23 for the paper web at the free end of the substantially vertical arm and a weight 24, selected as required, suspended from the free end of the substantially horizontal arm. The bearing 23 also has a free end, as the bearings 14, for easy removal of the paper web 15.

. It will be understood that means other than a pneumatic piston and cylinder assembly may be used for moving the frame 10 and that tension control of the paper web may be achieved by spring means. As an example of the sizes involved, the cylinder 5 may be 12 inches in diameter and the web 15 may be some 12 ft. in length.

For operation, a paper web of the appropriate length is formed into an endless loop and entrained round the bearings 14 and 23 and the impression roller 12 as shown in FIG. 1. There is nothing to interfere with this mounting of an already formed web. Assuming that the desired cylinder is already mounted on the shaft 6, that the appropriate ink supply is available and that the desired tension is applied, the motor 3 is started and drives the shaft 6 and the cylinder 5. The pneumatic assembly 16 is actuated by the counting device in such a way that the impression roller is lowered at the first transit of the aperture 18a past the photoelectric device 19 following the independent actuation of a manual print button. When the impression roller 12 is brought down against the cylinder 5 then, because of the extremely low inertia of the roller 12 and the minimum resistance offered by the air bearings 14, the web is rapidly accelerated to the correct speed. As soon as the pneumatic supply is transferred to the return entry of the double acting pneumatic assembly 16, either manually or in reponse to the photoelectric device 19, the return spring 17 with pneumatic assistance pushes the impression roller 12 clear of the cylinder 5. Again, because of the low inertia of the roller 12 the deceleration of the paper web is also rapid. The pneumatic supply for the air bearings is taken from one side of the supply to the pneumatic assembly 16 so that when the impression roller is returned to its initial, inoperative, position the pneumatic supply to the air bearings is cut off. These air bearings then cease to be low friction devices so that the deceleration of the paper web is made even more rapid.

The impression pressure is controllable by varying the pressure of the supply of air actuating the pneumatic assembly 16. The pressure is varied by means of a manually operated valve conveniently mounted on a control panel which is attached to the left hand side of the main frame 1 of the press. The pressure is read from a pressure gauge also mounted on the control panel. For clarity, the control panel, valve and pressure gauge are not shown in the figures.

We claim:

I. A printing press for printing on an endless loop web including a rotary printing cylinder, drive means coupled to said cylinder for driving the cylinder, guide means positioned near said cylinder and constructed for guiding said endless loop web so that the web passes adjacent the cylinder, said guide means comprising an idling impression roller having its axis parallel to the cylinder axis and means coupled to the impression roller for bringing the impression roller against the printing cylinder, with a portion of the web nipped therebetween, for a selectable duration, a reciprocatory body and means coupled thereto for reciprocatory the reciprocatory body, doctor blade means pivotably engaged against an edge of the body and arranged for cooperation with the printing cylinder, and adjustable means for clamping the doctor blade means in such a position that the doctor blade has a desired angle of contact with the printing cylinder, said clamping means comprising a threaded bore in said body, a screw cooperating with said threaded bore and projecting outwardly therefrom, and means pressing said doctor blade means against said edge and said screw.

2. A printing press for printing on an endless loop web including a rotary printing cylinder, drive means coupled to said cylinder for driving said cylinder, guide means positioned near the cylinder and constructed for guiding said endless loop web so that the web passes adjacent the cylinder, said guide means comprising an idling impression roller having its axis parallel to the cylinder axis and means coupled to the impression roller for bringing the impression roller against the printing cylinder, with a portion of the web nipped therebetween, for a selectable duration, a reciprocatory body and means coupled thereto for reciprocating the reciprocatory body, doctor blade means pivotably engaged against an edge of the body and arranged for cooperation with the printing cylinder, adjustable means for clamping the doctor blade means in such a position that the doctor blade has a desired angle of contact with the printing cylinder, a graduated rod affixed to said reciprocatory body, and a weight element slidably mounted on said rod, for applying a selectable torque to said body according to its position along said rod. 

1. A printing press for printing on an endless loop web including a rotary printing cylinder, drive means coupled to said cylinder for driving the cylinder, guide means positioned near said cylinder and constructed for guiding said endless loop web so that the web passes adjacent the cylinder, said guide means comprising an idling impression roller having its axis parallel to the cylinder axis and means coupled to the impression roller for bringing the impression roller against the printing cylinder, with a portion of the web nipped therebetween, for a selectable duration, a reciprocatory body and means coupled thereto for reciprocatory the reciprocatory body, doctor blade means pivotably engaged against an edge of the body and arranged for cooperation with the printing cylinder, and adjustable means for clamping the doctor blade means in such a position that the doctor blade has a desired angle of contact with the printing cylinder, said clamping meanS comprising a threaded bore in said body, a screw cooperating with said threaded bore and projecting outwardly therefrom, and means pressing said doctor blade means against said edge and said screw.
 2. A printing press for printing on an endless loop web including a rotary printing cylinder, drive means coupled to said cylinder for driving said cylinder, guide means positioned near the cylinder and constructed for guiding said endless loop web so that the web passes adjacent the cylinder, said guide means comprising an idling impression roller having its axis parallel to the cylinder axis and means coupled to the impression roller for bringing the impression roller against the printing cylinder, with a portion of the web nipped therebetween, for a selectable duration, a reciprocatory body and means coupled thereto for reciprocating the reciprocatory body, doctor blade means pivotably engaged against an edge of the body and arranged for cooperation with the printing cylinder, adjustable means for clamping the doctor blade means in such a position that the doctor blade has a desired angle of contact with the printing cylinder, a graduated rod affixed to said reciprocatory body, and a weight element slidably mounted on said rod, for applying a selectable torque to said body according to its position along said rod. 